Organizing pneumonia and occupational and environmental risk factors: a case-control study

A single-center case-control study was carried out to investigate the relationship between occupational and environmental exposure and organizing pneumonia (OP). Thirty-seven cases of OP, including 25 cases of cryptogenic OP, and 111 controls were included. Occupational exposure was assessed retrospectively by an industrial hygienist and an occupational physician, through semi-quantitative estimates of exposure. An exposure score was calculated for each subject, based on probability, intensity, daily frequency, and duration of exposure for each period of employment. The final cumulative exposure score was obtained by summing exposure scores for all periods of employment. Significant associations with all-cause OP were observed for exposure to tetrachloroethylene (OR 13.33, CI 95% 1.44-123.5) and silica (OR 6.61, CI 95% 1.16-37.71). A significant association with cryptogenic OP was observed only for tetrachloroethylene (OR 31.6, CI 95% 1.64-610.8). No associations were found for environmental exposure. Despite its low statistical power, this work suggests that occupational risk factors could be involved in OP.